The present invention relates generally to medical devices and methods, and more particularly to catheter devices and methods that are useable to form penetration tracts, fistulas or blood flow channels into target vessels in furtherance of a therapeutic purpose such as bypassing an arterial blockage, arterializing a vein, creating a dialysis fistula, or performing other interventional procedures.
In most regions of the world, atherosclerotic cardiovascular disease remains a major cause of premature death and morbidity. Various transluminal, catheter-based interventional techniques have been used, or proposed for use, to dilate or otherwise treat atherosclerotic obstructions that occur in coronary and/or peripheral arteries. These therapies have traditionally focused on treating the disease intraluminally, or from xe2x80x9cwithinxe2x80x9d the vessel lumen.
Included among the newer interventional techniques are certain percutaneous, transluminal techniques for bypassing obstructions in coronary or peripheral arteries through the use of the adjacent vein(s) as in situ bypass conduit(s); (e.g. using catheters to perform extra luminal procedures outside the diseased vessel lumen). These procedures include certain proprietary procedures known as PICVA(trademark) and PICAB(trademark) (PICVA(trademark) and PICAB(trademark) are trademarks of Transvascular, Inc. of Menlo Park, Calif.) as described in U.S. Pat. No. 5,830,222 (Makower) and in published PCT Applications WO 98/16161, WO 98/46119, WO99/49910 and WO99/49793. As described therein, in some instances, these procedures may be performed by a venous approach wherein a tissue penetrating catheter is inserted into a vein (the xe2x80x9chostxe2x80x9d vessel). The desired passageway or puncture is initially formed by facilitating the passage of a tissue penetrator (e.g., a flow of energy or an elongate penetration member) from the catheter, through the wall of the vein in which the catheter is positioned, and into a target location such as the lumen of an adjacent vessel (e.g. the artery). Alternatively, some of these procedures may be performed by an arterial approach wherein the catheter is inserted into an artery (the xe2x80x9chostxe2x80x9d vessel) and the desired passageway or puncture is initially formed by facilitating the passage of a tissue penetrator from the catheter, through the wall of the artery in which the catheter is positioned, and into the target location such as the lumen of an adjacent vessel (e.g. a vein). In some instances, the target vessel may be an artery.
In these procedures, the tissue-penetrating catheter must be placed in the proper longitudinal position and rotational orientation with respect to the target vessel prior to actuation or advancement of the tissue penetrator, to ensure that the tissue penetrator is aimed or positioned to enter the target vessel. To facilitate such aiming of the tissue penetrator, the tissue penetrating catheter may incorporate, or may be used in conjunction with, an imaging apparatus such as an intravascular ultrasound (IVUS) imaging apparatus to image the target vessel and possibly other structures. The image so obtained is then used to guide the longitudinal positioning and rotational orientation of the tissue penetrating catheter within the host vessel such that the penetrator will be aligned with the target and advancement or actuation of the tissue penetrator will result in the formation of the desired penetration tract between the host vessel and the target vessel.
Other techniques may also utilize a tissue penetrating catheter for infusion of medication into a vessel or other location, to place a guidewire into a vessel or other location, to form a channel into a vessel or other location through which other medical devices may be passed. For example, the tissue penetrating catheter may be inserted into any body cavity, such as the peritoneal cavity, adjacent a target vessel and the tissue penetrator used to access the target vessel. Indeed, certain procedures may be initiated from outside the body, with a tissue penetrating catheter or device used to penetrate into or gain access to a target vessel or other location within the body.
Various factors make accurate location of and subsequent penetration into a target vessel or other target location problematic. For example, although the general position of a target vessel or other target location may be known (e.g., certain coronary veins are expected to run parallel to certain coronary arteries), the anatomy of each patient may differ widely. Consequently, there is a need for a more accurate and repeatable technique for locating and penetrating into a target vessel or other target location, either from a host vessel or another starting location.
Applicants have determined that, in at least some of the procedures in which a penetration tract is formed between a host vessel (e.g., an artery such as a coronary artery) or starting location (e.g., body cavity or external location) and a target vessel (e.g., a coronary vein), it may be desirable to dilate at least a portion of the target vessel before advancement of the penetrator.
The present invention thus provides methods and apparatuses for temporarily dilating (i.e., distending, radially dilating, pressurizing or otherwise enlarging in transverse dimension) at least a portion of a target vessel to i) improve the imageability of the target vessel, and/or ii) decrease the distance that a penetrator must travel from a location where a penetrating catheter is positioned to the target vessel, and/or iii) allow for less precise aiming of the penetrator than would be required if the target vessel were not dilated, iv) improve the ability to advance a guidewire though the lumen of the target vessel and/or v) stiffen the wall of the target vessel to facilitate puncture thereof.
The dilation of the target vessel may be carried out by occluding flow through the vessel so as to cause an increase of pressure within the target vessel, or a target region within the vessel, and resultant dilation of the vessel. Alternatively, in areas where the blood pressure may be inadequate to cause the desired dilation of the target vessel, dilation may be caused by placing occluders in the vessel upstream and downstream of the region desired to be dilated and then infusing a fluid into the vessel between the occluders to thereby cause dilation of the vessel in the region between the occluders. Alternatively, the desired dilation of the target vessel may be carried out by placing a dilation member within the lumen of the vessel in the region into which the penetration is to be made and subsequently enlarging the dilation member so as to cause dilation (e.g., distension, bulging or stretching) of the wall of the vessel.
In accordance with the invention, there are provided vessel dilation catheters that incorporate one or more balloons, enlargeable members or other vessel dilating apparatus to cause the desired dilation of a target vessel. Also provided are systems that incorporate a vessel dilation catheter of the foregoing character in combination with tissue penetration catheters and ancillary equipment (e.g., guidewires, penetration tract enlarging apparatus, imaging apparatus, etc.) to create penetration tracts, fistulas, or flow channels between a starting location and a target vessel.
These aspects of the invention together with additional features and advantages thereof may best be understood by reference to the following detailed descriptions and examples taken in connection with the accompanying illustrated drawings.